Page 135 - TP_Prime_v2.2_Class_6
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Declaring and Initialising a Variable
In Python, variables are declared and initialised at the same time in the following way:
a = 10
b = 20
print ("a=", a)
print ("b=", b)
On the output screen, a = 10 and b = 20 will be printed. You can also assign the same value INTRODUCTION TO PYTHON
to multiple variables at the time in the following way:
a = b = 20
print ("a=", a)
print ("b=", b)
On the output screen, a = 20 and b = 20 will be printed. You can also assign multiple values
to multiple variables in the same line in the following way: 133
name, age, grade="Deepak", 12, ‘VII’
print ("Name is", name)
print ("Age is", age)
print ("Grade is", grade)
On the output screen, Name is Deepak, Age is 12 and Grade is VII will be printed.
Naming Conventions for Variables
Before we specify any variable name, we must follow the Python rules:
• Variable names can contain letters (a-z, A-Z), digits (0-9), or an underscore (_).
• Variable names must begin with a letter or an underscore.
• Variable names are case-sensitive (Age and age are different variables).
• Python keywords cannot be used as variable names (reserved words like if, else,
for, etc.).
• Variable names cannot contain spaces.
Examples of valid variables are:
Employee_num Answer_value Variable1 Cz67ys
Examples of invalid variables are:
1Variable (Cannot start with a digit)
Employee Num (Space in the middle)
BookPrice$ (‘$’ sign is not accepted)
break (Reserved keyword)

